Studies on dual-functioning of bio-absorbable scaffold materials and cells for the rehabilitation of oral tissues

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The findings obtained are described in the following four categories.(1) Studies on the preparation of bio-absorbable scaffold materials : We succeeded in producing inter-connected porous sponges by freeze-drying from natural materials (collagen and gelatin) and synthetic materials (alginate and poly(lactide-caprolacton)).(2) Studies on the cell culture : We investigated the effect of medium type (alfa-ME or DME), serum amount, dexamethasone induction and the growth factors (e.g. TGF-beta) on the proliferation and differentiation of rat bone marrow stromal cells and osteoblastic MC3T3-E1 cells. The former cells required the addition of vitamin C and the serum amount of more than 10% for the cell proliferation. The dexamethasone and the growth factors appeared to accelerate the osteogenic differentiation.(3) Studies on the duplex-functioning of the cells and scaffold materials : we successfully cultured the rat bone marrow stromal cells in the collagen gel frame-worked by poly (lactide- caprolacton) sponge. We examined the degree of osteogenic differentiation of rat bone marrow stromal cells cultured in the collagen gel. With the DME medium supplemented with vitamin C, the cells could differentiate into the pre-osteoblasts with their phenotype characterized by the appearance of mRNA for osteopontin. The cells in this stage appear to contribute to the rehabilitation of lost oral hard tissues in the future.(4) Studies on the tissue reaction against the scaffold materials : We implanted prepared scaffold materials (collagen gel, collagen sponge, poly (lactide-caprolacton) sponge, and gelatin hydro-gel) in the back tissue of SD rats, and evaluated the histo-pathological reaction against these scaffold materials. All scaffold materials were mildly absorbed by the host tissue without any strong pathological reaction.